Tris-dipicolinate Cerium Complexes Bearing Dications of Arginine, Histidine, and Ornithine

Abstract

Five tris-dipicolinate cerium (III and/or IV) complexes having dications of L-arginine (Arg), L-histidine (His) or L- ornithine (Orni), namely (H₂Arg)[Ce(dpc)₃].7H₂O (1), (H₂His) [Ce(dpc)₃].4H₂O (2), (H₂Orni)[Ce(dpc)₃].7H₂O (3), (H₂His)(HPy) [Ce(dpc)₃]. 4H₂O (4), and (H₂Orni)(HPy)[Ce(dpc)₃].7H₂O (5) (dpc = dipicolinate, Py = pyridine) are synthesized and characterized. The cerium (IV) complexes (1, 2, 3) have one dication of the amino acids, whereas the cerium (III) complexes (4, 5) have one dication of amino acid together with one pyridinium cation. The role of the charge on the metal ion in the packing patterns is discussed and compared with bis-dipicolinate complexes of first row transition metal.

Keywords:

• amino acid dication
• cerium dipicolinate complexes
• crystal structures
• nine-coordination number

Acknowledgments

The authors thank Department of Science and Technology, New Delhi, India, for financial support for X-ray facility.